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Forum: Riesel Prime Search 2021-01-26, 07:13
Replies: 233
Views: 35,099
Posted By bur
I only saw this now, sorry. Sounds convincing at...

I only saw this now, sorry. Sounds convincing at first, but why not use 2 out of 10 threads, or 7 or all?

Fundamentally you have two methods to remove a candidate for good, TF or PRP. If one is...
Forum: And now for something completely different 2021-01-21, 07:36
Replies: 3
Views: 282
Posted By bur
I checked other primes of this person and he/she...

I checked other primes of this person and he/she often uses primes or primorials as k. So I assumed it was about having k's with many or few small factors.

But you're right, maybe I'm giving it...
Forum: And now for something completely different 2021-01-20, 12:51
Replies: 3
Views: 282
Posted By bur
Correction: Should read "high weight". And...

Correction: Should read "high weight".

And now that I thought about it some more, k = 1153#-1 is a large k with few small factors but more elegant than using a 486 digit prime. Maybe that's the...
Forum: And now for something completely different 2021-01-20, 09:43
Replies: 3
Views: 282
Posted By bur
2^1571237 · (1153# - 1) + 1 - why was it constructed like that?

2^1571237 * (1153# - 1) + 1 is a new prime submitted to PrimePages (https://primes.utm.edu/primes/page.php?id=131592).

It is almost a PrimoProth...
Forum: Data 2021-01-12, 11:40
Replies: 5
Views: 4,202
Posted By bur
From the Primo FAQ...

From the Primo FAQ (http://www.ellipsa.eu/public/primo/primo.html#FAQ):
For serious prime search you might as well setup a Linux machine, but for just playing around it would be nice to have a...
Forum: Riesel Prime Search 2020-12-16, 09:08
Replies: 88
Views: 20,289
Posted By bur
I find it really inspiring how long you've been...

I find it really inspiring how long you've been working on this k. I started sieving for Proth k=1281979 some months back, now I'm at around 250T as well, but only for n < 4.1M. So 2 cores produce a...
Forum: Riesel Prime Search 2020-12-14, 07:05
Replies: 233
Views: 35,099
Posted By bur
If the same computer doing the sieving could...

If the same computer doing the sieving could eliminate candidates faster by using PRP, what's the advantage of sieving? Or vice versa.
Forum: And now for something completely different 2020-11-11, 18:18
Replies: 13
Views: 900
Posted By bur
Two questions... ;) Firstly: why choose...

Two questions... ;)


Firstly: why choose the form x + y * z# +1? It's specifically the x + ... I don't get. If you want to go for N-1, wouldn't that require a product + 1? So why not test x * z#...
Forum: And now for something completely different 2020-11-10, 18:15
Replies: 40
Views: 13,429
Posted By bur
Does anyone know if the lists are still actively...

Does anyone know if the lists are still actively maintained? And is the search organized in any way? PG has a generalized C/W project, but it only covers bases up to 140 or so. Where did the others...
Forum: Proth Prime Search 2020-10-18, 15:42
Replies: 27
Views: 9,775
Posted By bur
At PG forum it was said that sr1sieve is supposed...

At PG forum it was said that sr1sieve is supposed to be faster than sr2sieve for fixed k, so I wanted to give it a try, but cannot find binary for windows. Deoes someone have a link? Thanks.

...
Forum: Math 2020-10-14, 17:20
Replies: 12
Views: 1,304
Posted By bur
Having looked at the proof, what I don't get is,...

Having looked at the proof, what I don't get is, why is 2^{(2r+1)s}=(2^s + 1)(...)?

Wolfram expressed it differently as (2^a)^b = (2^a + 1)(2^{a(b-1)}-2^{a(b-2)}+...). For that proof, I don't...
Forum: Math 2020-10-14, 13:02
Replies: 12
Views: 1,304
Posted By bur
Ok, thanks. So 2^n+1 is proven to only be prime...

Ok, thanks. So 2^n+1 is proven to only be prime if it is a Fermat number.
Forum: Math 2020-10-14, 12:14
Replies: 12
Views: 1,304
Posted By bur
Not really related to this specific question, but...

Not really related to this specific question, but also a question about 2^n + 1:


Why aren't they researched in regard to being prime? It is basically a Proth number with k = 1. I just checked...
Forum: Software 2020-10-03, 06:01
Replies: 9
Views: 1,523
Posted By bur
Sorry, but I still don't get it. Using 2^n + 1...

Sorry, but I still don't get it. Using 2^n + 1 for the first 10 values we get:



3 5 9 17 33 65 129 257 513 1025


5 divides the 2nd, 6th and 10th candidate. So it divides not at most every...
Forum: Software 2020-09-29, 17:10
Replies: 9
Views: 1,523
Posted By bur
For the record, common sieving software DOES...

For the record, common sieving software DOES check all candidates in the sieve against a prime factor. The reason why you almost never see a prime dividing more than one candidate is simply that the...
Forum: Software 2020-09-14, 08:13
Replies: 9
Views: 1,523
Posted By bur
The thing is, what does happen is that a single...

The thing is, what does happen is that a single candidate is factored by more than one prime in a relatively small range.

The sieve file contains 65000 candidates and I was sieving in four...
Forum: Software 2020-09-13, 16:32
Replies: 9
Views: 1,523
Posted By bur
I don't really get it. The candidates aren't a...

I don't really get it. The candidates aren't a million consecutive numbers. Only the n is consecutive.

Say my primes are of magnitude 1E12 and candidates are k * 2^1E6 + 1. Then any of the primes...
Forum: Software 2020-09-12, 05:47
Replies: 9
Views: 1,523
Posted By bur
General question about sieving software

I'm not sure if this is the proper section, but anyway.

Sieve of Eratosthenes takes a prime, marks all multiples of it, then moves to the next unmarked number and so on. But when I view the output...
Forum: Riesel Prime Search 2020-09-09, 20:46
Replies: 399
Views: 54,917
Posted By bur
Here are the n values for Riesel primes with k =...

Here are the n values for Riesel primes with k = 1281979 and n <= 100000


3
7
43
79
107
157
269
Forum: Riesel Prime Search 2020-09-09, 09:54
Replies: 399
Views: 54,917
Posted By bur
Haha, I just realized this is probably trivial...

Haha, I just realized this is probably trivial and occurs for every divisor... yes, I'm not that good at math. :)
Forum: Riesel Prime Search 2020-09-09, 07:21
Replies: 399
Views: 54,917
Posted By bur
I looked into the matter why only primes show up...

I looked into the matter why only primes show up as n for low n values. Here are some restrictions I found:

If n \equiv 0 \textrm{ mod } 2 the Riesel number will be divisible by 3 (n = 2, 4, 6, 8,...
Forum: Riesel Prime Search 2020-09-08, 20:02
Replies: 399
Views: 54,917
Posted By bur
But then I would say low weight doesn't really...

But then I would say low weight doesn't really matter. Either I test 100000 candidates for a given k and find 10 primes or I test 10000 and find one. Then move to the next low weight k and in the end...
Forum: Riesel Prime Search 2020-09-08, 16:59
Replies: 399
Views: 54,917
Posted By bur
So the number of primes per n decreases stronger...

So the number of primes per n decreases stronger than the number of candidates per n?


Here are the n values that produce Riesel primes:

1281979 * 2^n - 1
0 <= n <= 20000

3
7
Forum: Riesel Prime Search 2020-09-08, 07:44
Replies: 399
Views: 54,917
Posted By bur
kar_bon, I never really understood the Nash...

kar_bon, I never really understood the Nash weight. It is an indicator for how many candidates remain after sieving? So I would think a low weight is good, since few candidates after sieving is...
Forum: Riesel Prime Search 2020-09-08, 05:39
Replies: 399
Views: 54,917
Posted By bur
I was testing k = 1281979 for n<= 100000 and...

I was testing k = 1281979 for n<= 100000 and interestingly the first 10 n for which this is prime are prime themselves. After that unfortunately there's n = 1005 which obviously isn't. But the ratio...
Showing results 1 to 25 of 39

 
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